578
FXUS63 KTOP 171132
AFDTOP
Area Forecast Discussion
National Weather Service Topeka KS
632 AM CDT Sat Mar 17 2018
...Update to aviation forecast discussion...
.SHORT TERM...(Today and tonight)
Issued at 317 AM CDT Sat Mar 17 2018
Early this morning water vapor imagery showed the shortwave that
tracked over the outlook area yesterday progressing northeastward
into Iowa, with the CWA remaining under stratus cloud cover on the
back edge of this exiting low. Despite this cloud cover, a tight
pressure gradient remained in place over the area, resulting in
breezy northwesterly winds still supporting enough CAA to drop low
temperatures into the 30s this morning.
Models show a mid-level ridge and surface high pressure sliding into
the central U.S. today and tonight behind this exiting system,
resulting in dry conditions. As this surface high gradually
progresses southeastward across the CWA, winds will veer from
northwest to north-northeast by early this evening and will become
easterly by Sunday morning. Despite this advancing surface high
pressure, models show the low stratus cloud cover behind the exiting
low lingering through this morning and very slowly retreating to the
northeast through the afternoon hours. However there are still some
model discrepancies with regards to how quickly this cloud cover
will scatter out from southwest to northeast across the CWA to allow
more sunshine to peak through to support better diurnal heating this
afternoon. Due to this uncertainty in the exact timing of this
diminishing cloud cover, there is uncertainty in today`s temperature
forecast as afternoon high temperatures will be very dependent upon
when this cloud cover scatters out. In general, short-range models
seem to be trending slower with this diminishing cloud cover, so
have decreased temperatures by a few degrees for today with highs
only reaching into the upper 40s to upper 50s. Any lingering clouds
will exit far northeast Kansas early this evening, but expect some
increasing cloud cover by sunrise Sunday morning as the next surface
low and mid-level shortwave begin to move into Kansas.
.LONG TERM...(Sunday through Friday)
Issued at 317 AM CDT Sat Mar 17 2018
The next storm system will quickly take aim at the region by Sunday.
A vigorous upper trough will take on a negative tilt before closing
off Sunday night across northern OK. Sfc low pressure will develop
across SE CO with some WAA/moisture advection forecast to develop by
Sunday afternoon so rain chances should gradually increase from
south to north late in the day with much better chances Sunday night
into Monday as the upper system tracks across northern OK. One point
of uncertainty in this forecast however is how far north the
stronger moisture transport/deeper moisture will get with EC showing
a southern trend to the storm track which keeps better rain chances
west or south of the CWA. In any case there`s modest MUCAPE Sunday
night into early Monday so there may be isolated t-storms especially
across the sw parts of the CWA Sunday night but do not anticipate
any severe storms.
The longwave pattern will gradually amplify through mid week with NW
flow across the Plains which will keep temps near avg with mainly
dry weather. Upper ridge will build into the region by Thursday with
warmer and breezy conds. The next chance for precip appears to be
Friday as the next upper trough begins to move into the Plains.
&&
.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 629 AM CDT Sat Mar 17 2018
For the 12z TAFs, stratus cloud cover over the TAF sites will
result in MVFR cigs persisting through at least early this
afternoon before gradually scattering out through early this
evening. The breezy northwesterly winds from early this morning
will steadily diminish today, with winds veering to the northeast
and east by this evening and overnight.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Hennecke
LONG TERM...Omitt
AVIATION...Hennecke